Radiopaque fluorocarbon (C8F17Br) is a uniquely different radiodense molecule. The chemical, physical and biological properties are such that it is a very useful x-ray contrast agent for diagnostic studies. Extensive animal investigations and initial human tests have proven the efficacy of this compound in bronchography, alveolography and gastroenterography. Preliminary animal studies indicate that radiopaque fluorocarbon is also non-toxic and effective in ventriculomyelography, lymphography, angiography and arthrography. The objectives of these experiments are to evaluate thoroughly neat liquid C8F17Br and flurocarbon emulsions as contrast agents in the areas of application mentioned above. Different emulsions will be prepared to obtain low toxicity, appropriate viscosity, surface coating and adequate radiodensity for diagnostic work with conventional roentgenographic equipment. These experiments will be performed in experimental animals of different species.